This was his 400th career goal in Europe's top five leagues, making him the first player to reach that tally.
Andreas Pereira has said that Manchester United's performance against Chelsea in the Premier League on Saturday has left them feeling "pumped up" for the upcoming Champions League clash with Juventus.
Ronaldo will return to Manchester United with Juventus aiming to fire the Serie A giants to a third consecutive Champions League victory.
With Genoa struggling to contain the lively Cancelo down the right Juve were firmly in control, their only regret at the break being they weren't further in front.
Manafort To Be Sentenced Feb. 8
Ellis his client is suffering from "significant issues" with his health as he requested the judge expedite Manafort's sentencing. Manafort was convicted of eight counts in the tax and fraud trial in the Eastern District Court of Virginia earlier this year.
The 18th-minute strike is Ronaldo's fifth in nine Serie A appearances for the Bianconeri.
Energised, the 23-year-old should have levelled seconds later, outjumping Leonardo Bonucci but his header went wide.
The result gives Napoli the chance to close to within four points of Juve at the top of the table and sees their 11-game winning run in all competitive competitions come to an end just three days before they face Manchester United in the Champions League.
Juventus paid heavily for failing to restrain Genoa when Daniel Bessa headed a cross from Christian Kouame into the back of the net at 67 minutes.
Ronaldo's only outing against Mourinho's United was in the 2017 UEFA Super Cup, featuring for seven minutes as a substitute in Madrid's 2-1 win.